Hi there. I had trouble with this. Best way that worked for me was download wallet of satoshi app on my phone and then paste wallet address from there into your nostr profile lightning address. Then you will be able to recieve bitcoin if domeone likes your post or whatever
Discussion
This is good advice. WoS may require a VPN connection through a nonUS country though because the ambiguity of US policy led them to leave the US market last I heard. Some nostr clients have this VPN capability built in (like Amethyst, an Android only client) called Tor.